Injectors



Filed March 19, 1959 IO l8 INVENTOR. RAMOND J. CAROLAN ATTORNEY United States Patent INJECTORS Raymond J. Carolan, Prairie Village, Kans., assignor to The Bendix Corporation, a corporation of Delaware Filed Mar. 19, 19s9, Ser. No. 800,465

3 Claims. Cl. 230-412 This invention relates to injectors of the type in which a jet of fluid propelled into a passage past an opening draws another fluid through an opening into the passage. It has been found especially suitable for use in oxygen regulators which supply oxygen mixed with varying proportions of air, for example, to aviators breathing masks. In certain types of such regulators the oxygen under pressure passes through an injector in which it entrains air, forming a mixture of air and oxygen for breathing. The quantity of oxygen required by the aviator, and the correct proportion of oxygen to air, both vary with changes in altitude, requiring an arrangement which provides for changing these factors as the altitude changes.

Available injectors are capable of producing with satisfactory accuracy the correct proportions and quantities of entraining and entrained fluids, respectively, as the rate of supply of the entraining fluid varies. Among the objects of this invention are the provisions of an injector having even greater proportioning accuracy, capable of manufacture at lower cost and exhibiting increased performance repeatability and reliability. This is accomplished in general by the provision of a resilient nozzle having a nozzle opening automatically variable in accordance with variations in the supply pressure of the entraining fluid.

It has been discovered that a conical nozzle, in which both the inner and outer walls are conical, is especially advantageous. The inner wall directs the aspirating fluid toward an orifice at the apex there to emerge as a uniform jet stream whereas the conical outer wall defines a symmetrical wall thickness about the orifice permitting continuous and uniform variation in orifice size with variations in entraining or aspirating fluid pressure.

These qualities are especially advantageous because of the nature of the flow control and aspiration problem in breathing oxygen regulators used in high performance aircraft. An aviator needs a uniformly greater proportion of oxygen as altitude is increased until, at about thirty thousand feet, he must breathe one hundred percent oxygen. The respiratory gas is supplied to him in response to inhalation demand. At higher altitudes oxygen must be supplied at increasing positive pressures. Thus gas flow rate is variable over a wide range from low flow rates incident to shallow breathing to very high flow rates occasioned by deep gasps and by the need for positive pressure.

The injector structure of the regulator must be equal to these requirements. The combination of failure to be supplied oxygen when it is demanded and the physical discomfort experienced by the pilot as gravitational forces change during maneuvering of a high performance craft may result in inability of the pilot to take advantage of the full capability of his craft and may even result in a dangerous feeling of panic.

It is an object of this invention to provide an injector equal to this problem and which is sufiiciently simple Patented May 23, 1961 "ice in construction to insure reliable and uniform performance.

Other objects and advantages of the invention, including the specific object of elimination of moving parts and sliding seals, will hereinafter be apparent.

The single figure of the drawing is a sectional view of a portion of a demand type oxygen breathing regulator embodying the invention and is taken on a plane parallel with the axis of the regulator injector structure.

In the drawing, the regulator housing is identified by the numeral 10. The housing defines a passageway .12 for oxygen, here the entraining fluid, and a passageway 14 for air, here the entrained fluid. The numeral 16 designates an aneroid operated dilution air inlet controller, only the end of which is shown, and the numeral =18 designates the demand valve head which is operated by an inhalation responsive or demand dia phragm, not shown, to admit oxygen to passage '12. Beginning at shoulder 20, this passage is enlarged in the downstream direction. The annular flange 22 of a nozzle 24 is held sealed against shoulder 20 by the upstream end of an injector tube 26 which, in turn, is held in place by an abutment of its downstream end against a mixing tube 28 threaded into passageway 12.

Ambient air admitted by the dilution air regulator 16 passes through air passage 14 and is aspirated through a cutout 30 in injector tube 26 by oxygen emerging from the orifice 32 at the apex of the nozzle 24. The air entrained joins and flows with the oxygen through the injector tube 26 and mixing tube 28 to a mask connection, not shown.

Both the inner and outer walls of the nozzle are advantageously conical so that its wall thickness is substantially uniform. The inner wall directs the oxygen toward the orifice with minimum turbulence there to emerge into the injector tube with uniform aspirating effect. An increase in the pressure of oxygen upstream of the nozzle will result in the latter being stretched to increase the size of the orifice opening 32 to accommodate a larger volume of flow at greater velocity for increased aspirating effect. Upon reduction in upstream oxygen pressure, the renitence of the nozzle material, preferably a silicone rubber, is eflective to reduce the orifice size. The nozzle orifice is disposed proximately to the junction of the air and oxygen passageways so that the air will be aspirated into the oxygen stream.

Since aspiration effect is determined by entraining gas velocity and since this in turn is a function of orifice area and pressure differential across the orifice, the problem is to make the orifice area variable with pressure differential so that the quantity of flow and the proportions of air and oxygen in the flow can be satisfactorily controlled together, for a given required air to oxygen proportion, by simply actuating the demand valve to vary the oxygen pressure applied to the nozzle.

I claim:

1. For an air dilution type oxygen breathing regulator including a housing; an air aspirating oxygen injector structure comprising an oxygen flowpath and an intersecting air flow path defined by the regulator housing, and a nozzle comprising a conical element open at its base and apex and having resilience permitting the apex opening to vary in size over the normal range of oxygen flow, said nozzle having a peripheral base portion disposed in sealing engagement with the walls of the oxygen flow path upstream from said intersection and having its apex extending downstream in said oxygen flow path and terminating proximately to said intersection.

2. An air aspirating oxygen injector structure for an oxygen regulator including, an injector housing, an oxygen flow path of circular section defined by said housing an end abutting said flange, the nozzle being formed,

of resilient material and extending axially. into said injector tube with an orifice openingformed at itsapex;

a cutout formed in a wall of said injector tube pr0ximately to said apex, and an air flowpath formed-by said housing intersecting with and opening into said cutout.

3. In an air dilution type oxygen breathing regulator including a housing, an oxygen supply valve and an air inlet; an oxygen injection and air aspirating structure comprising, an oxygen flow path including said supply valve, an air flowpath communicating with said air inlet and intersecting said oxygen flow path downstream from said oxygen supply valve, a nozzle in the oxygen fiowpath downstream from said supply valve extending across said flowpath and having an orifice opening disposed in aspirating proximity to said intersecting air flowpath, the nozzle being'formed of resilient material responsive to variationsin oxygen pressure at its upstream side to alter the size of said orifice.

References Cited in the file of this patent UNITEDL STATES I PATENTS 2,595,737 Von-Rotz Mayv 6, 1952 

